Endocrine system

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Endocrine system

• Endocrine glands secrete hormones into the blood
  where they affect tissue elsewhere to influence
  bodily growth, development, activity and repair. 
  Hormone output depends largely on negative
  feedback processes.  The main endocrine glands
  include the pituitary, thyroid, adrenals,
  pancreas, testes and ovaries.

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Endocrine System

• Glands, Hormones, Responsibility,
• too much or too little of the hormones,
  symptoms, treatments

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endocrine system

• Next to the nervous system the endocrine
  system is the system that controls the body. 
  However, the endocrine system uses hormones to
  stimulate the metabolic activities of the cells. 
  These hormones are released into the blood
  stream.  Tissue response to hormones usually
  occur after a lag time of seconds or days.  Once
  started the responses tend to be much more
  prolonged  than those that are induced by the
  nervous system.

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endocrine system

•      The organs of the endocrine system are small
  and unimpressive.  The endocrine glands of the
  body include the pituitary, thyroid, parathyroid,
  adrenal, pineal, and thymus.
•      Hormones are chemical compounds that
  regulate metabolic function of cells in the
  body.  There are two types of hormones amino
  acid-based hormones and steroids.  Most hormones
  are amino acid-based.  Steroid hormones are
  synthesized from cholesterol.  Only the gonadal
  hormones and adrenocortical hormones are
  steroids.

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endocrine system

• The endocrine system is a complex network of
  chemical signals and messages that control many
  immediate and life-long bodily responses and
  functions.
• Growing taller, developing male or female
  characteristics and reacting to fear are all
  partially directed by endocrine hormones.

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endocrine system

• maintains the body's internal steady state
  (nutrition, metabolism, excretion, water and salt
  balance) reacts to stimuli from outside the
  body regulates growth, development and
  reproduction and produces, uses and stores
  energy.

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endocrine glands-male

• 1. Hypothalamus
• 2. Pituitary gland
• 3. Pineal gland (epiphysis)
• 4. Thyroid gland
• 5. Parathyroid glands
• 6. Thymus
• 7. Adrenal (suprarenal)
• 8. Pancreas
• 9. Gonads (testes)

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endocrine glands- female

• Hypothalamus
• 2. Pituitary gland
• 3. Pineal gland (epiphysis)
• 4. Thyroid gland
• 5. Parathyroid glands
• 6. Thymus
• 7. Adrenal (suprarenal)
• 8. Pancreas
• 9. Gonads (ovaries)

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endocrine system's three parts

• glands
• hormones
• target cells
• They relay information and instructions
  throughout the body. Sometimes the whole process
  works within seconds, say, in response to fear.
  Other times it reacts more slowly, telling body
  parts when and how much to grow and developing
  characteristics that distinguish male from
  female.

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• Acting like a communication network, it responds
  to stimuli by releasing hormones, the chemical
  messengers that carry instructions to target
  cells throughout the body, from endocrine glands.
  
• The target cells read and follow the hormones'
  instructions, sometimes building a protein or
  releasing another hormone. These actions lead to
  many bodily responses such as a faster heart beat
  or bone growth.

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endocrine system

• There are over 50 hormones in the human body,
  and they can be grouped together by their
  chemical structure.
• Steroids are produced from cholesterol. 
• Peptides are chains of amino acids. 
• Other hormones are derived from amino acids. 

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hypothalamus

• The hypothalamus is a region of the brain that
  controls an immense number of bodily functions.
  It is located in the middle of the base of the
  brain, and encapsulates the ventral portion of
  the third ventricle. This pattern of vascular
  connections is presented here diagrammatically.

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pituitary gland 

• Found at the base of the skull, this
  comprises the anterior and posterior pituitary. 
  The anterior pituitary produces hormones
  stimulating the thyroid, adrenal cortex, ovarian
  follicles, ovaries and testes.  The posterior
  pituitary influences smooth muscle and the
  kidneys with hormones from the brains
  hypothalamus.  That also largely controls hormone
  output from the anterior pituitary gland.

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pituitary gland

• 1. hypothalamus
• 2. pituitary gland
• 2a. pituitary stalk
• 3. optic chiasma
• 4. pineal gland
• 5. corpus callosum
• 6. pons
• 7. cerebellum
• 8. sphenoid bone
• 8a. sella turcica

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pituitary gland

• The pituitary gland is often portrayed as the
  "master gland" of the body. Such praise is
  justified in the sense that the anterior and
  posterior pituitary secrete a battery of hormones
  that collectively influence all cells and affect
  virtually all physiologic processes.
• http//www.pituitary.org.uk/resources/di.shtml

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King ?

• The pituitary gland may be king, but the power
  behind the throne is clearly the hypothalamus. As
  alluded to in the last section, some of the
  neurons within the hypothalamus - neurosecretory
  neurons - secrete hormones that strictly control
  secretion of hormones from the anterior
  pituitary. The hypothalamic hormones are referred
  to as releasing hormones and inhibiting hormones,
  reflecting their influence on anterior pituitary
  hormones.

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Growth hormone (GH)

• Growth hormone controls growth in children and
  aspects of general metabolism in adults. In
  children, lack of growth hormone inhibits the
  child's growth. The child will be smaller than
  other children his or her age and may look
  younger, but will be normally proportioned. About
  a third of children with growth hormone
  deficiency are also overweight. This is because
  growth hormone also controls the fat under the
  skin. These children are not necessarily
  overeating. It is important to ensure they
  receive a balanced diet and a reasonable amount
  of exercise.

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TSH

• As an example, thyroid-releasing hormone from
  the hypothalamus binds to receptors on anterior
  pituitary cells called thyrotrophs, stimulating
  them to secrete thyroid-stimulating hormone or
  TSH. The anterior pituitary hormones enter the
  systemic circulation and bind to their receptors
  on other target organs. In the case of TSH, the
  target organ is the thyroid gland.

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Gonadotrophins

• These hormones control sex and reproduction.
  The two sex hormones made by the pituitary are
  luteinising hormone (LH) and follicle stimulating
  hormone (FSH). In women, these hormones are sent
  through the bloodstream from the pituitary to the
  ovaries, where they control ovulation. They are
  thus essential for a normal menstrual cycle and
  for fertility. In men, these hormones are sent to
  the testes, where LH stimulates the production of
  the male hormone testosterone, and FSH is
  important in sperm production. In children, LH
  and FSH control sexual development during
  puberty.

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Posterior lobe of pituitary produces vasopressin
and oxytocin
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Diabetes insipidus

• DI is a disorder in which your kidneys are
  unable to retain water. This results in the
  production of large volumes of urine which in
  turn makes you feel dry and very thirsty. DI is
  not related to the type of diabetes most people
  have heard of, diabetes mellitus. In DI, there is
  no problem with the sugar in the blood or urine.
  The problem either concerns the lack of a
  water-retaining hormone or chemical in the blood
  (called vasopressin sometimes anti-diuretic
  hormone) or is sometimes due to an abnormality in
  the kidneys which prevents them from responding
  to this hormone. The hormone itself is normally
  secreted by the pituitary gland.

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Oxytocin stimulates smooth muscle
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Melatonin and the Pineal Gland

• The pineal gland is a tiny structure located
  at the base of the brain. Its principal hormone
  is melatonin, a derivative of the amino acid
  tryptophan. Synthesis and release of melatonin
  is stimulated by darkness and inhibited by light.
  But even without visual cues, the level of
  melatonin in the blood rises and falls on a daily
  (circadian) cycle with peak levels occurring in
  the wee hours of the morning.

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Pineal Gland

• Production of melatonin varies with periods of
  light and darkness in the environment. Even
  though in human beings the pineal gland lies near
  the centre of the brain, it obtains information
  about light in the environment through nerve
  pathways originating in the eyes. In general,
  light slows and darkness stimulates the pineal
  gland's production of melatonin. Therefore, the
  gland tends to secrete small amounts of melatonin
  during the day and larger amounts at night.

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Pineal Gland

• In human beings, melatonin has been linked to
  the onset of puberty, the stage of life when a
  person matures sexually. Studies have shown that
  the pineal gland's nightly secretion of melatonin
  decreases when a boy or girl reaches puberty.
  Other studies have indicated that melatonin may
  help regulate menstrual cycles in women and sperm
  production in men. In addition, researchers have
  suggested a connection between melatonin levels
  and certain mental illnesses.

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Thyroid gland 

• This gland at the front of the neck produces
  hormones increasing metabolic rate. Thyroid
  hormones affect three fundamental physiologic
  processes cellular differentiation, growth, and
  metabolism. If you think about that statement for
  a minute, you might legitimately ask "So what
  else is there?" which emphasizes just how much of
  physiology is affected by thyroid hormones. Not
  many hormones can claim as diverse a set of
  target cells.
• The related parathyroid glands control calcium
  levels in blood.

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thyroid gland 

• This gland at the front of the neck produces
  hormones increasing metabolic rate.  The related
  parathyroid glands control calcium levels in
  blood.

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Thyroid gland

• 1. Thyroid gland
• 1a. Right lobe
• 1b. Left lobe
• 1c. Isthmus
• 2. Thyroid cartilage
• 3. Trachea
• 4. Subclavian artery

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Thyroid and Parathyroids

• The thyroid gland also produces another
  hormone called calcitonin, and the parathyroid
  glands secrete parathyroid hormone. Parathyroid
  hormone and calcitonin participate in control of
  calcium and phosphorus homeostasis and have
  significant effects on bone physiology.

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Parathyroids behind thyroid

• 1a. Right lobe
• 1b. Left lobe
• 9. Inferior thyroid artery
• 10. Parathyroid glands

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Pancreas 

• This controls blood-sugar levels by insulin
  and glucagon secreted into the duodenum from the
  islets of Langerhans in the pancreas.

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Pancreas

• 1a. Head
• 1b. Body
• 1c. Tail
• 1d. Pancreatic duct
• 1e. Cells secreting digestive juices
• 1f. Islets of Langerhans
• 3. Common bile duct
• 4. Spleen
• 5. Duodenum

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What is Cushing's and how do we get it?

• Cushing's is a disorder in which two small
  glands above your kidneys (the adrenal glands)
  are making too much of a hormone called cortisol.
  The most common reason for Cushing's is the use
  of steroid drugs to treat other conditions such
  as asthma, arthritis or colitis. If such a cause
  has been counted out, then several other
  possibilities will be explored. One is that the
  pituitary gland may be sending too much of a
  hormone called ACTH to the adrenal glands.

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What does it feel like to have Cushing's?
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Adrenals

• Right kidney
• 2. Left kidney
• 3. Aorta
• 4. Inferior vena cava
• 5. Adrenal (suprarenal) glands
• 5a. Capsule
• 5b. Cortex
• 5c. Zona glomerulosa
• 5d. Zona fasciculata
• 6. Medulla

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Thymus 

• Located behind the sternum (breastbone) this
  may influence growth and sexual maturation.  It
  shrinks after puberty.

thymus of a newborn child
thymus in an adult
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Ovaries

• In females from puberty onward these produce
  the hormones estrogen and progesterone between
  them determining female secondary sexual
  characteristics and preparing the uterus for
  pregnancy.  Ovulation - the bursting of a ripe
  ovum from an ovarian follicle - is influenced by
  hormones from the pituitary gland.

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Testes

• In males from puberty onward these produce
  testosterone, responsible for secondary sexual
  characteristics.

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references

• Cyber-Anatomy Web site http//library.thinkquest.o
  rg/11965/cyber-anatomy_index.html
• Pituitary Foundation
• http//www.pituitary.org.uk/resources/di.shtml
• The Endocrine System
• krupp.wcc.hawaii.edu/BIOL100/present/endocrin/sld0
  32.htm

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pituitary and ovulation

• 1. Pituitary gland
• 1a. Anterior lobe
• 1b. Posterior lobe
• 2. Ripening follicle
• 3. Ovulation
• 4. Active corpus luteum
• 5. Degenerating corpus luteum
• 6. Estrogen
• 7. Follicle stimulating hormone
• 8. Luteinising hormone
• 9. Progesterone

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What is acromegaly?

• Acromegaly is a disease of the pituitary
  gland. Your pituitary gland is a small, but very
  important, gland at the base of your brain behind
  the bridge of your nose. Sometimes it can be
  affected by a tumour. These are almost invariably
  benign rather than cancerous and therefore do not
  spread anywhere else. Acromegaly is caused when
  your pituitary gland has a tumour which produces
  too much growth hormone.